1. Field of Invention
This invention relates generally to a method and apparatus for orienting, positioning and spin printing indicia on pellet shaped articles, such as pharmaceutical capsules and the like. More specifically, the invention relates to a method and apparatus in which a conveyer transports the pellet shaped articles to a rotating printing drum that maintains the pellet shaped articles within pockets as the pellet shaped articles are passed through a printing station. The printing station has a movable printing roller capable of being moved toward and away from the printing drum or vice versa such that the printing roller accurately spin prints indicia onto the pellet shaped articles. A servo controller unit is connected to the apparatus and is configured to control the location of the printing roller with respect to the rotating printing drum to adjust the amount of indicia transferred to the pellet shaped articles.
2. Description of Related Art
The concept of providing solid medication in unit doses for oral consumption is well known and commercially available wherever pharmaceutical products are sold. The medicinal compounds are packaged for consumption in various well known forms, such as tablets, caplets, capsules and others. The present invention is generally concerned with the orienting, rectifying, and precision spin printing of indicia onto pellet shaped articles.
The capsule is known as a common method of packaging medicinal compounds and other materials suitable for ingestion. Typically, the capsule is a two-part pellet shaped article having telescoping cap and body portions of predetermined size and configuration to hold the medicine therein, while caplets are shaped like capsules, but are one piece. Standard practice in the packaging of capsules is to imprint certain indicia over the surface of the capsules. The name of the manufacturer or the batch number from which the medicinal compound has been derived, or other information which may be required by the Food and Drug Administration, or other government agencies, are examples of the types of indicia found on capsules. The indicia can be imprinted onto the capsules by a technique known in the art as spin printing.
Spin printing is carried out by rotating the capsule on its longitudinal axis as indicia is printed on the surface of the capsule. Preferably, the capsules will be uniformly oriented or rectified before reaching the printing station. At the printing station, the capsules are then uniformly rotated in a manner which allows for rotation of the capsule without any substantial slippage between the imprinting head and the capsule surface, whereby a sharp, precise, printing indicia is produced on each capsule as it passes through the printing station.
Numerous methods and machines have been developed to spin print indicia onto pellet shaped articles, such as pharmaceutical capsules, food products, and the like. In general, there are two types of methods and corresponding apparatuses for spin printing. The first apparatus and method spin prints pellet shaped articles using a flat type carrier apparatus, e.g., conveyor belt, while the second apparatus and method spin prints onto the pellet shaped articles using rotating drums or cylinders.
The conveyor belt type spin printing apparatus, as shown in U.S. Pat. No. 3,871,295, for example, typically includes a feeding station 20, a transporting and rectifying member 21, a conveyance system 31, and a spin printing unit 41. The feeding station 20 usually comprises a gravity feed hopper located above the transporting member 21 and is designed to frictionally feed randomly ordered articles C into cavities 24 of the transporting member 21 in an orderly manner. The transporting member 21, which usually provides at least one rotating drum having a plurality of peripherally spaced cavities, rectifies the pellet shaped articles C while they are still in the cavities and deposits them in a predetermined and uniform manner onto the conveyance system 31.
The conveyance system, as shown in U.S. Pat. No. 4,632,028 for example, typically includes a carrier bar 45 having pockets 52 for holding the deposited articles 2 therein. The carrier bars 45 are conventionally composed of a slippery material, such as, for example, polytetraflouroethylene, having a coefficient of friction which is less than that of the printing roll in the spin printing unit. This composition allows the pellet shaped articles 2 to rotate freely upon their longitudinal axis when subjected to the frictional influence of the printing roll during the spin printing process. Before the articles are transported through the spin printing unit, some of the conveyor belt type spin printing devices use an apparatus for spacing apart the cap and body portions of the article to a limited degree in order to provide an enlarged and exact overall length for each pellet shaped article, thereby preparing each article for the spin printing operation.
For example, in U.S. Pat. No. 3,868,900, the cap and body portions are separated by using an air jet 72, known in the industry as an air separator. Once the articles are prepared for spin printing, they are transported further downstream to a spin printing unit. The conventional conveyor belt type spin printing unit also comprises an ink reservoir which applies ink to an etched roll. The etched roll transfers the indicia to a rubber printing roll which prints indicia onto each article as it passes through the printing unit while on the conveyance system.
Examples of the conveyor belt type of spin printing apparatus are disclosed in U.S. Pat. Nos. 3,868,900 to Ackley; 3,871,295 to Ackley; 3,931,884 to Ackley; 4,069,753 to Ackley, deceased et al.; 4,104,966 to Ackley, Jr. et al.; 4,167,226 to Ackley, decreased et al.; 4,254,704 to Ackley, Sr. et al.; 4,266,477 to Ackley; 4,335,810 to Ackley, deceased et al.; 4,372,437 to Ackely, Sr. et al.; 4,413,556 to Ackley; 4,479,573 to Ackley, Sr. et al.; and 4,632,028 to Ackley.
The rotating drum type spin printing apparatus, as shown in U.S. Pat. No. 4,377,971 for example, typically includes a feeding station, a plurality of rotating drums and a spin printing station. The feeding station 1 is similar to the one described in conjunction with the conveyor belt type spin printer and will not be discussed here. The rotating drums and usually comprise at least two, and sometimes additional rotating drums. The first rotating drum 5, or transfer drum, receives the randomly ordered pellet shaped articles 3 into a plurality of peripherally spaced pockets 9 shaped and sized in a manner well known in the art to receive and carry individual pellet shaped articles 3. In general, a vacuum source 83 retains the pellet shaped articles 3 in the pockets 9 while a rotary brush 17 sweeps away any pellet shaped article 3 that may be overlapping the article-filled pocket. An arcuate sizing block and back guide 23, which is positioned circumferentially over the transfer drum 5 downstream of the feeding station 1 and upstream of the other drum 46, facilitates the rectifying of the pellet shaped articles 3 while in the peripherally spaced pocket 9 so that they are radially aligned within the pockets 9 of the transfer drum 5. Optionally, once the pellet shaped articles 3 are rectified, an air check may help to move the pellet shaped articles from the feed drum 5 to a second, or cam drum 46.
As shown in U.S. Pat. No. 3,889,591 for example, the second rotating drum 18 may also retain the pellet shaped articles T in peripherally spaced pockets 17a using a vacuum source 29. As mentioned with the transfer drum above and shown in U.S. Pat. No. 4,394,933 having three rotating drums, the second rotating drum 36 may also have a sizing block and back guide 44 that is positioned circumferentially over the second rotating drum 36 downstream of the transfer drum and upstream of the other drum, to facilitate the orienting of the pellet shaped articles 12 so that they are longitudinally aligned within the pockets 38 of the second rotating drum 36. The longitudinally aligned articles 12 are then transferred to a rotating printing drum 52.
The printing drum 52 maintains the pellet shaped articles 12 within peripherally spaced pockets 50a and rotates the articles 12 through a printing unit 58 where they are spin printed upon. It should be noted that while in the printing drum, the articles have been known to be held in place by a vacuum source. By keeping the pellet shaped articles in place, the vacuum source controls the amount the articles spin when they come into contact with the print roller. Since the print roller is rotating faster than the drum, the article "spins" in its pocket, thereby printing some indicia on the article. The spin printed articles are then discharged from the apparatus for further processing. Examples of the rotating drum type of spin printing apparatus are disclosed in U.S. Pat. Nos. 3,889,591 to Noguchi; 4,266,478 to Ackley; 4,369,702 to Ackley; 4,377,971 to Ackley; and 4,394,933 to Ackley.
Unfortunately, both types of spin printers suffer from drawbacks. One drawback to these types of spin printing devices is that there is no mechanism to accurately control the amount of pressure that is applied from the printing roll to the rotating article. Therefore, the existing types of spin printers apply too much or too little pressure to the article. When too much pressure is applied, the article rotates too fast within the pocket, and as such, will contact the printing roll an undesirable additional number of times. This relationship is known in the industry as kiss-back, which results in uneven and undesired indicia being printed onto the article. As a solution to this problem, some manufacturers cut-away the non-indicia transferring region of the printing roll to prevent kiss-back from occurring. However, this approach has proven to be too costly and results in the cut-away portion of the roll being wasted. An additional drawback is that the printing roll must be changed for different indicia logos. Also, because the above-described types of spin printing devices are not capable of controlling the amount of pressure applied to the article, the devices cannot print a band of indicia completely around the article such that the ends of the indicia bands are registered. Further, conventional spin printers have the drums and printing roller geared to one another, which does not allow for the relative speed changes. At present, the current spin printing apparatuses are capable of printing a band of indicia on the article encompassing approximately 310.degree. to 320.degree. around the article. In addition, existing spin printing apparatuses are incapable of adjusting the speed of rotation of the printing roller relative to the printing drum, the amount of pressure applied to the articles from the printing roller, the location of the printing roller and articles relative to each other and/or the amount of indicia applied to the articles "on the fly," or in other words, while the apparatus is operating.